Support Harvester extension, add installation info

[torchiaf]

Summary

Fixes #12322

Occurred changes and/or fixed issues

Technical notes summary

Areas or cases that should be tested

The Harvester extension and extension's repo are not yet available.
To test the functionality, just change the related IDs in dev:

export const HARVESTER_REPO = 'harvester-ui-extension';
export const HARVESTER_EXTENSION = 'harvester';

Areas which could experience regressions

Screenshot/Video

New Installation info - admin

New Installation info - standard user

Full view

Checklist

• The PR is linked to an issue and the linked issue has a Milestone, or no issue is needed
• The PR has a Milestone
• The PR template has been filled out
• The PR has been self reviewed
• The PR has a reviewer assigned
• The PR has automated tests or clear instructions for manual tests and the linked issue has appropriate QA labels, or tests are not needed
• The PR has reviewed with UX and tested in light and dark mode, or there are no UX changes

[a110605]

Overall is good.

I would suggest to add hyperlink https://github.com/harvester/harvester-ui-extension.git on the word Harvester repository or directly display https://github.com/harvester/harvester-ui-extension.git in the first point.

As a Rancher user, I don't know what's harvester extension and where is its github repository.

[torchiaf]

@nwmac I agree with Andy to add the link to the harvester GitHub repository and possibly improve the spelling. WDYT ?

[torchiaf]

@a110605 I've updated the text and add the link to harvester repo

[a110605]

LGTM

[aalves08]

Gave it a test and after adding the repo I got:

After mimicking the install by changing the variable mentioned in the instructions to an installed extension (ex: elemental):

I would say that LGTM